#!/usr/bin/env ruby

# Copyright (C) 2019 Open Source Robotics Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

require 'optparse'
require 'yaml'

# List of required keys in each YAML file.
#  - format: Format of the YAML file. This version has to be supported by this
#            script.
#  - library_version: Expected library version to work with the conf file.
#  - library: Name of the shared library that will handle the commands.
#  - commands: List of top level commands supported by the library, as well as
#              a brief description.
required_tags =
  {
    '1.0.0' => %w[format library_name library_version library_path commands]
  }

commands = {}
yaml_found = false

conf_dirs = '@CMAKE_INSTALL_PREFIX@/share/ignition/'
conf_dirs = ENV['IGN_CONFIG_PATH'] if ENV.key?('IGN_CONFIG_PATH')
conf_dirs = conf_dirs.split(':')

conf_dirs.each do |conf_directory|
  next if Dir.glob(conf_directory + '/*.yaml').empty?

  yaml_found = true

  # Iterate over the list of configuration files.
  Dir.glob(conf_directory + '/*.yaml') do |conf_file|
    next if conf_file == [',', '..'].any?

    # Read the configuration file.
    yml = YAML.load_file(conf_file)

    # Sanity check: Verify that the content of the file is YAML.
    unless yml && yml.is_a?(Hash)
      puts "Configuration warning: File [#{conf_file}] does not contain a "\
           'valid YAML format. Ignoring this configuration file.'
      next
    end

    # Sanity check: Verify that the the configuration file format is supported.
    unless yml.key?('format') && required_tags.key?(yml['format'])
      puts "Configuration error: File [#{conf_file}] uses format "\
           "#{yml[format]} but this version is not supported."
      exit(-1)
    end

    # Sanity check: Verify that the format of the conf file is correct.
    required_tags[yml['format']].each do |tag|
      # Verify that the YAML file contains the needed keys.
      unless yml.key?(tag)
        puts "Configuration error: File [#{conf_file}] has a missing key. "\
             "Make sure that the file contains '#{tag}'."
        exit(-1)
      end

      # Verify that the value for this key is not empty.
      next if yml[tag]
      puts "Configuration error: File [#{conf_file}] does not contain any "\
           "value for the key '#{tag}'."
      exit(-1)
    end

    yml['commands'].each do |cmd|
      cmd.each do |key, value|
        # Sanity check: Verify that we have a non-empty key and value.
        unless key && value
          puts "Configuration error: File [#{conf_file}] contains an empty "\
               "value in the 'commands' section."
          exit(-1)
        end

        # Sanity check: A 'help' command is not allowed.
        if key.eql? 'help'
          puts "Configuration error: File [#{conf_file}] contains a command "\
               "named 'help' but this is a reserved name."
          exit(-1)
        end

        # Sanity check: Verify that a command has not been used before by other
        # library.
        if commands.key?(key) &&
           commands[key].values[0]['library_name'] != yml['library_name']
          puts "Configuration error: File [#{conf_file}] contains a command "\
               'already registered by '\
               "#{commands[key].values[0]['library_name']}."
          exit(-1)
        end

        # Create a hash where the command is the key and the value contains all
        # the additional information (in a hash).
        if !commands.key?(key)
          commands[key] =
            { yml['library_version'] =>
              {
                'library_name' => yml['library_name'],
                'library_path' => yml['library_path'],
                'description' => value
              } }
        else
          new_value = {}
          new_value[yml['library_version']] =
            {
              'library_name' => yml['library_name'],
              'library_path' => yml['library_path'],
              'description' => value
            }
          commands[key].update(new_value)
        end
      end
    end
  end
end

# Check that we have at least one configuration file with ign commands.
unless yaml_found
  puts "I cannot find any available 'ign' command:\n"\
       "\t* Did you install any ignition library?\n"\
       "\t* Did you set the IGN_CONFIG_PATH environment variable?\n"\
       "\t    E.g.: export IGN_CONFIG_PATH=$HOME/local/share/ignition\n"
  exit(-1)
end

# Use an auxiliary hash to sort the commands ordered by version. Newest
# versions go first.
sorted_commands = {}
commands.each do |cmd, versions|
  sorted_commands[cmd] = versions.sort.reverse
end

# Commands is a hash where the key is the command and the value is a list.
commands = sorted_commands

# Debug: show the list of available commands.
# puts commands

# Read the command line arguments.
usage = 'The \'ign\' command provides a command line interface to the ignition'\
        " tools.\n\n"\
        "  ign <command> [options]\n\n"\
        "List of available commands:\n\n"\
        "  help:          Print this help text.\n"

# Used to align the commands and the description.
padding_width = 15
commands.each do |cmd, versions|
  # Calculate the padding to add between the command and the description.
  padding_to_apply = padding_width - cmd.size - 1
  padding = ''
  padding_to_apply.times do
    padding += ' '
  end

  usage += '  ' + cmd + ':' + padding + versions.first[1]['description'] + "\n"
end

usage += "\nOptions:\n\n"\
         "  --force-version <VERSION>  Use a specific library version.\n"\
         "  --versions                 Show the available versions.\n"\
         '  --commands                 Show the available commands.'

usage += "\nUse 'ign help <command>' to print help for a command.\n"

OptionParser.new do |opts|
  opts.banner = usage
end.parse

# The user wants to show the available commands.
if ARGV.include?('--commands')
  commands.each_key do |cmd|
    puts cmd
  end

  exit(0)
end

# Check that there is at least one command and there is a plugin that knows
# how to handle it.
if ARGV.empty? || (ARGV[0] != 'help' && !commands.key?(ARGV[0]))
  puts usage
  exit(-1)
end

# The 'help' command is managed here.
if ARGV[0].eql? 'help'

  # Sanity check: Verify that there is a known command after help.
  unless ARGV.size == 2 && commands.key?(ARGV[1])
    puts usage
    exit(0)
  end

  # Remove the help command and append --help.
  ARGV.delete_at(0)
  ARGV.append('--help')
end

version_index = 0

# The user wants to use a specific version of the command.
if ARGV.include?('--force-version')
  i = ARGV.index('--force-version')

  # Sanity check: Verify that there is an argument after --force-version
  unless ARGV.size >= i + 2
    puts usage
    exit(-1)
  end
  required_version = ARGV.at(i + 1)

  # Sanity check: The version value shouldn't start with '-' or '--'.
  if required_version.start_with?('-', '--')
    puts usage
    exit(-1)
  end

  # Sanity check: Verify if we have the command for the specified version.
  found = false
  commands[ARGV[0]].each_with_index do |version, index|
    next unless version.first.eql?(required_version)
    found = true
    version_index = index
    break
  end

  unless found
    puts 'Version error: I cannot find this command in '\
         "version [#{required_version}]."
    exit(-1)
  end

  ARGV.delete_at(i)
  ARGV.delete_at(i)
end

# The user wants to show the available versions.
if ARGV.include?('--versions')
  commands[ARGV[0]].each do |version|
    puts version.first
  end

  exit(0)
end

# Read the plugin that handles the command.
cmd_rb_library = commands[ARGV[0]].at(version_index)[1]['library_path']

# Pass the request to the specific ruby library.
require cmd_rb_library
cmd = Cmd.new

# Set the process title to something nice.
Process.setproctitle("ign #{ARGV.join(' ')}")

cmd.execute(ARGV)
